JP6334741B2 - Process for the preparation of halogenated alkenes by dehydrohalogenation of halogenated alkanes - Google Patents

Description

  The present invention relates to a process for preparing (hydro) (chloro) fluoroalkenes, and in particular to preparing (hydro) (chloro) fluoroalkenes by catalytic dehydrohalogenation of hydrochlorofluorocarbons. Regarding the method.

  The listing or discussion of information or prior published documents in this specification should not necessarily be taken as an acknowledgment that the information or documents are part of the state of the art or are common general knowledge.

  (Hydro) (chloro) fluoroalkenes such as (hydro) (chloro) fluoropropene can be prepared from the corresponding hydrochlorofluoroalkanes by dehydrochlorination. This transformation can be accomplished by contacting the hydrochlorofluoroalkane with the catalyst under suitable conditions, either thermally, ie, by thermal decomposition, or typically the hydrochlorofluoroalkane is converted to an alkali metal hydroxide, etc. Can be caused chemically by contact with a strong base of

  However, the preparation of (hydro) (chloro) fluoroalkenes, for example by catalytic dehydrochlorination, is often problematic due to competing dehydrofluorination reactions. Competing dehydrofluorination reactions can produce unwanted by-products that should be removed or recycled. As a result, the dehydrochlorination reaction typically has a lower selectivity than desired for the desired (hydro) (chloro) fluoroalkene product.

  Thus, there is a need for a method that suppresses any undesirable competing dehydrofluorination reactions and correspondingly increases selectivity for the desired (hydro) (chloro) fluoroalkene. Such a method would increase both the yield of the desired (hydro) (chloro) fluoroalkene product and the single pass productivity of the reaction.

  The present invention involves contacting a reagent stream comprising hydrochlorofluoroalkane in a reactor with a catalyst to dehydrochlorinate at least a portion of the hydrochlorofluoroalkane to produce (hydro) (chloro) fluoroalkene and hydrogen chloride. Addressing the foregoing and other deficiencies by providing a method for the preparation of (hydro) (chloro) fluoroalkenes by producing a product stream comprising (HCl), the catalyst comprising a metal oxide catalyst, a metal halogen Selected from the group consisting of a fluoride catalyst, a zerovalent metal catalyst, a carbon-based catalyst, and mixtures thereof; (i) the catalyst is chlorinated prior to contacting it with a reagent stream comprising a hydrochlorofluoroalkane, and / or Or (ii) the contacting step is performed in the presence of HCl co-feed.

(Hydro) (chloro) fluoroalkenes and hydrochlorofluoroalkanes Preferably, the process of the invention comprises C _3-7 (hydro) (chloro) by dehydrochlorination of the corresponding C _3-7 hydrochlorofluoroalkane. For preparation of fluoroalkenes.

Advantageously, the C _3-7 (hydro) (chloro) fluoroalkene prepared by the process of the present invention is (hydro) (chloro) fluorobutene or (hydro) (chloro) fluoropropene. Thus, in one embodiment, the method of the invention is directed to the preparation of (hydro) (chloro) fluoropropene by dehydrochlorinating the corresponding hydrochlorofluoropropane.

For clarity and brevity, the remainder of this specification relates to the preparation of (hydro) (chloro) fluoropropene unless otherwise indicated. Of course, the present invention is not limited to the preparation of (hydro) (chloro) fluoropropenes, and where appropriate, any of the foregoing information may be used for C _4-7 or more (hydro) (chloro) fluoroalkenes. It should be understood that it is applicable to preparation.

  The term (hydro) (chloro) fluoropropene includes hydrochlorofluoropropene, hydrofluoropropene, and perfluoropropene. Similarly, the term (hydro) (chloro) fluoroalkene includes hydrochlorofluoroalkene, hydrofluoroalkene, and perfluoroalkene, and the term (hydro) (chloro) fluorobutene includes hydrochlorofluorobutene, hydrofluorobutene, And perfluorobutene.

Preferred hydrochlorofluoropropenes that can be prepared by the process of the present invention include 1-chloro-3,3,3-trifluoropropene (CF ₃ CH═CHCl, HCFO-1233zd) and 2-chloro-3,3,3. - it includes trifluoroacetic chloropropene such trifluoropropene _{(CF 3 CCl = CH 2,} HCFO-1233xf).

HCFO-1233zd is 1,2-dichloro-3,3,3-trifluoropropane (CF ₃ CHClCH ₂ Cl, HCFC-243db) and / or 1,1-dichloro-3,3,3-trifluoropropane ( CF ₃ CH ₂ CHCl ₂ , HCFC-243fa) can be prepared according to the process of the present invention by dehydrochlorination. Preferably, HCFO-1233zd is prepared by dehydrochlorinating HCFC-243fa. When specified for the avoidance of doubt, both the cis and trans isomers of HCFO-1233zd are included within the scope of the present invention.

HCFO-1233xf is 1,2-dichloro-3,3,3-trifluoropropane (CF ₃ CHClCH ₂ Cl, HCFC-243db) and / or 2,2-dichloro-3,3,3-trifluoropropane ( CF ₃ CCl ₂ CH ₃ , HCFC-243cb) can be prepared according to the process of the present invention by dehydrochlorination. Preferably, HCFO-1233xf is prepared by dehydrochlorinating 243db.

  Hydrofluoropropenes that can be prepared by the method of the present invention include trifluoropropene, tetrafluoropropene, and pentafluoropropene, preferably trifluoropropene and tetrafluoropropene, especially tetrafluoropropene.

3,3,3-trifluoropropene (CF ₃ CH═CH ₂ , HFO-1243zf) is 1-chloro-3,3,3-trifluoropropane (CF ₃ CH ₂ CH ₂ Cl, HCFC-253fb) and Preferred trifluoropropenes that can be prepared according to the present invention by dehydrochlorination of 2-chloro-3,3,3-trifluoropropane (CF ₃ CHClCH ₃ , HCFC-253da). Preferably, HCFO-1243zf is prepared by dehydrochlorinating 253fb.

1,3,3,3-tetrafluoropropene (CF ₃ CH═CHF, HFO-1234ze) is 1-chloro-1,3,3,3-tetrafluoropropane (CF ₃ CH ₂ CHClF, HCFC-244fa) And / or preferred tetrafluoropropenes that can be prepared according to the present invention by dehydrochlorination of ₂ -chloro-1,3,3,3-tetrafluoropropane (CF ₃ CHClCH ₂ F, HCFC-244db). Preferably, HFO-1234ze is prepared by dehydrochlorinating 244fa. When specified for the avoidance of doubt, both the cis and trans isomers of HFO-1234ze are included within the scope of the present invention.

2,3,3,3-tetrafluoropropene (CF ₃ CH═CHF, HFO-1234yf) is 1-chloro-2,3,3,3-tetrafluoropropane (CF ₃ CHFCH ₂ Cl, HCFC-244eb) And / or another preferred tetrafluoropropene that can be prepared according to the present invention by dehydrochlorination of 2-chloro-2,3,3,3-tetrafluoropropane (CF ₃ CFClCH ₃ , HCFC-244bb). Preferably, HFO-1234yf is prepared by dehydrochlorinating 244bb.

Pentafluoropropenes that can be prepared according to the method of the present invention include 1,2,3,3,3-pentafluoropropene (CF ₃ CF═CFH, HFO-1225ye) and 1,1,3,3,3-penta tetrafluoropropene _{(CF 3 CH = CF 2,} HFO-1225zc) is included. HFO-1225ye is 2-chloro-1,2,3,3,3-pentafluoropropane (CF ₃ CFClCH ₂ F, HCFC-235bb) and / or 1-chloro-1,2,3,3,3- A preferred pentafluoropropene that can be prepared by dehydrochlorination of pentafluoropropane (CF ₃ CFHCHFCl, HCFC-235ea). When specified for the avoidance of doubt, both the cis and trans isomers of HFO-1225ye are included within the scope of the present invention.

Perfluoropropene (CF ₃ CF═CF ₂ , 1216) is 2-chloro-1,1,2,3,3,3-hexafluoropropane (CF ₃ CFClCF ₂ H, HCFC-226ba) and / or 1-chloro. It can be prepared according to the method of the present invention by dehydrochlorinating -1,1,2,3,3,3-hexafluoropropane (CF ₃ CFHCF ₂ Cl, HCFC-226ea).

Catalyst The catalyst used in the method of the present invention comprises one or more of (a) a metal oxide, (b) a metal halide, (c) a zerovalent metal, or (d) a carbon-based catalyst. In one aspect of the invention, the catalyst comprises one or more of (a) a metal oxide, (b) a metal halide, or (c) a zerovalent metal. In embodiments, the catalyst comprises one or more of (a) a metal oxide or (b) a metal halide. Preferably, the catalyst comprises a metal oxide.

  As explained in more detail below, in use, each of the four classes of catalysts will be at least partially chlorinated. Thus, for example, in use, a metal oxide catalyst can be considered a metal (oxy) chloride (typically a metal oxychloride) and a metal halide catalyst can be considered a metal (halo) chloride. . Optionally, the catalyst is fluorinated prior to in-use chlorination or pre-chlorination. In use, the catalyst can also be fluorinated with any HF present due to competing dehydrofluorination of the hydrochlorofluoroalkane. Thus, in use, each of the four classes of catalysts can be at least partially chlorinated and at least partially fluorinated. Thus, for example, in use, a metal oxide catalyst can be considered a metal (oxy) (fluoro) chloride, typically a metal oxyfluorochloride.

  The form of the catalyst can vary depending on, for example, the nature of the catalyst and / or the nature of the particular (hydro) (chloro) fluoropropene being prepared. The catalyst may contain components added to improve catalyst activity, stability, and / or ease of preparation. For example, see the discussion below regarding promoters that can be used in metal oxide catalysts. Alternatively / additionally, when shaping or granulating the catalyst into the desired form, the catalyst may contain binders and / or lubricants to improve the physical integrity of the catalyst. Magnesium stearate is an example of a suitable lubricant / binder. Another suitable lubricant / binder is graphite. When present, the binder and / or lubricant is typically present in an amount of about 0.1 to about 10% by weight of the catalyst, preferably about 0.2 to about 6% by weight of the catalyst.

  The catalyst used herein can be unsupported or supported on any suitable substrate. For example, “The design and Preparation of Supported Catalysts”, G.M. J. et al. K. See Acres et al., Catalysis, 1981 (RSC), which is incorporated herein by reference for suitable catalyst supports. Typical catalyst supports include, for example, activated carbon, graphite, chlorinated graphite, and combinations thereof. As described later in this specification, activated carbon and graphite, in addition to being suitable catalyst supports, are also suitable catalysts for good reasons for the process of the present invention. The catalyst of the present invention may be provided in any suitable form, including, for example, small pills or granules of a size suitable for use in a fixed bed or fluidized bed.

A first class of catalysts suitable for use in the process of the present invention are catalysts comprising metal oxides. Typically, the metal in the metal oxide catalyst is one or more of any metal that forms a metal (oxy) chloride or metal (oxy) (fluoro) chloride having the characteristics of a Lewis acid. Examples are Li, Na, K, Ca, Mg, Cs, Al, Sc, Y, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Re, Fe, Ru, Co, Rh , Ir, Ni, Pd, Pt, Cu, Ag, Au, Zn, La, and Ce. In one embodiment, the metal in the metal oxide is Li, Na, K, Ca, Mg, Cs, Cr, Al, Zr, Nb, Pd, Ta, Zn, V, Mo, Ni, Co, and their Selected from mixtures. In another embodiment, the metal in the metal oxide is a transition selected from Cr, Zr, Nb, Ta, V, Mo, Pd, Ni, Zn, Co (particularly Cr and Zn), and mixtures thereof. It is a metal. In a further embodiment, the metal in the metal oxide is a Group I or Group II metal selected from Li, Na, K, Ca, Mg, and Cs. Examples of preferred metal oxides include Cr ₂ O ₃ , ZrO ₂ , Li ₂ O, Na ₂ O, K ₂ O, CaO, MgO, Cs ₂ O, and mixtures thereof. Catalysts based on Cr ₂ O ₃ (chromia) are particularly preferred in certain embodiments.

  In use, the metal oxide catalyst is typically a metal (oxy) (fluoro) chloride. This is because at least some oxygen in the lattice of the metal oxide or metal (oxy) fluoride (if the metal oxide is prefluorinated in use and / or the catalyst is fluorinated with HF). This is because, according to the method of the present invention, chlorine can be replaced by a pre-chlorination step and / or by a co-feed of HCl. In other words, a metal oxide (or metal (oxy) fluoride if the metal oxide is prefluorinated) can be considered a precatalyst.

  The metal oxide catalyst used in the process of the present invention may contain at least one additional metal or compound thereof. This can also be referred to as a metal promoter. In one embodiment, the at least one additional metal is Li, Na, K, Ca, Mg, Cs, Sc, Al, Y, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn , Re, Fe, Ru, Co, Rh, Ir, Ni, Pd, Pt, Cu, Ag, Au, Zn, La, Ce, and mixtures thereof. Preferably, the at least one additional metal is selected from Li, Na, K, Ca, Mg, Cs, Cr, Zr, Nb, Pd, Ta, Zn, V, Mo, Ni, Co, and mixtures thereof. The

For clarity, to avoid doubt, the additional metal (or compound thereof) cannot be the same as the metal in the same oxidation state of the metal oxide for any given catalyst. For example, if the catalyst comprises an oxide of chromium (III), the at least one additional metal can be any suitable metal, including the metals listed in the previous section, other than chromium (III). Further, when the catalyst comprises an oxide of chromium (III), the at least one additional metal (or compound thereof) can be a compound of chromium (VI). In a preferred embodiment, the additional metal compound is an additional metal oxide, chloride, or oxychloride. A preferred additional metal for the Cr ₂ O ₃ based catalyst is zinc or a compound of zinc. Such zinc promoted chromia catalysts are often referred to as zinc / chromia catalysts.

  When present, the total amount of additional metal or compound of additional metal present in the catalyst of the present invention is typically from about 0.01% to about 25% by weight, based on the total weight of the catalyst. The preferred amount of additional metal or compound of additional metal is from about 0.1% to about 20%, conveniently from about 0.1% to about 15%. In some embodiments, the catalyst is an additional metal in an amount from about 0.5% to about 10% by weight of the catalyst, such as from about 1 to about 8%, such as from about 1 to about 5% by weight of the catalyst. Or contain additional metal compounds.

  It is to be understood that the amount of additional metal or additional metal compound cited herein refers to the amount of elemental metal, whether present as elemental metal or a compound of metal.

  The metal oxide catalyst used in the present invention may be commercially available and / or prepared by any suitable means. The metal oxide catalyst is typically prepared by a precipitation process whereby the target metal oxide is precipitated from a solution of the target metal salt when treated with an alkali or base. For example, chromium (III) oxide can be prepared by precipitation when treated with a chromium (III) nitrate salt solution containing aqueous ammonia. Such metal oxide catalysts are produced commercially, for example by BASF and Johnson-Matthey.

  By way of example only, a suitable process for preparing a zinc / chromia catalyst that can be used in the process of the present invention is summarized below. Further details of zinc / chromia catalysts and their preparation can be found, for example, in European EP-A-0502605, European EP-A-0773061, European EP-A-0957704, International Patent Application No. 98/10862, And in International Patent Application No. 2008/040969, which is incorporated herein by reference.

  Suitable methods for the preparation of the zinc / chromia catalyst include coprecipitation from a solution of zinc nitrate and chromium nitrate in the addition of ammonium hydroxide. Alternatively, surface impregnation of zinc or their compounds onto an amorphous chromia catalyst can be used.

  Further methods for preparing zinc / chromia catalysts include, for example, reduction of chromium (VI) compounds such as chromate, dichromate, especially ammonium dichromate to chromium (III) with zinc metal, Subsequent coprecipitation and washing, or mixing a chromium (VI) compound and a compound of zinc, such as zinc acetate or zinc oxalate as a solid, and heating the mixture to an elevated temperature to form chromium (VI) compound chromium ( III) Inducing reduction to an oxide to oxidize a compound of zinc to zinc oxide.

  Zinc can be introduced into the chromia catalyst in the form of a compound, for example, nitrate, halide, oxyhalide, oxide, or hydroxide, and / or chromia catalyst, depending at least in part on the catalyst preparation technique used. Can be introduced above. In cases where the catalyst preparation is by impregnation with chromia, halogenated chromia, or chromium oxyhalide, the compound is preferably a water-soluble salt, such as a halide, nitrate, or carbonate, used as an aqueous solution or slurry. Alternatively, zinc and chromium hydroxides are co-precipitated (eg, by using a base such as sodium hydroxide, potassium hydroxide, or ammonium hydroxide, or a mixture of such bases) and then converted to the oxide, A zinc / chromia catalyst can be prepared. Mixing and grinding the insoluble zinc compound with the basic chromia catalyst provides a further method of preparing the catalyst precursor. A method for making a zinc / chromia catalyst based on chromium oxyhalide comprises adding a compound of zinc to a hydrated chromium halide.

  A second class of catalysts suitable for use in the process of the present invention are those containing metal halides. The halide in the metal halide catalyst can be any halide selected from fluoride, chloride, bromide, and iodide, preferably fluoride or chloride. However, in use, the metal fluoride, bromide, or iodide will be a metal (halo) chloride (in the case of halo = fluoride, bromide, or iodide). This is because at least some of the halides in the metal halide lattice are replaced with chlorine by a pre-chlorination step and / or a co-feed of HCl according to the method of the present invention. Optionally, the catalyst undergoes a pre-fluorination step in the pre-chlorination step and / or prior to chlorination with a co-feed of HCl. In such circumstances, and / or because the catalyst may be at least partially fluorinated by any HF present in the reactor as a result of competing hydrochlorofluoroalkane dehydrofluorination, Metal halide catalysts in use can be considered metal (fluoro) (halo) chlorides (halo = bromide or iodide).

  Typically, the metal in the metal halide catalyst is Li, Na, K, Ca, Mg, Cs, Sc, Y, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Re , Fe, Ru, Co, Rh, Ir, Ni, Zn, La, Ce, and mixtures thereof. In one embodiment, the metal in the metal halide is selected from Li, Na, K, Ca, Mg, Cs, and mixtures thereof. In another embodiment, the metal in the metal halide is selected from Cr, Zr, Nb, Ta, Fe, V, Mo, Pd, Ni, Zn, Co (particularly Cr and Zr), and mixtures thereof. Transition metal.

  Metal halide catalysts can be commercially available and / or can be prepared by any suitable means. For example, suitable metal hydroxides, oxides, and / or carbonates can be dissolved in aqueous HCl and / or HF in a corrosion resistant container. After evaporating to dryness, the resulting sample can be calcined at an elevated temperature, preferably in the presence of an inert gas such as nitrogen. Typically, the resulting material is ground into a fine powder, preferably formed into small circles or granules.

  A third class of catalysts suitable for use in the process of the present invention are catalysts containing zero valent metals. Zero valent metal catalysts typically include zero valent metals selected from Fe, Co, Ni, Cu, Mo, Cr, Mn, Pd, Pt, Nb, Rh, and mixtures thereof. Suitable catalysts include (active) carbon, nickel, and palladium supported on alloys of the aforementioned metals. Suitable alloys include stainless steel, Monel®, and Inconel®. A catalyst comprising nickel is currently particularly preferred.

  In use, the zerovalent metal catalyst is typically at least partially chlorinated by a pre-chlorination step and / or a co-feed of HCl according to the method of the present invention. In use, the zero valent metal catalyst can also be at least partially fluorinated with any HF produced by dehydrofluorination of competing hydrochlorofluoroalkanes. In other words, at least some zero valent metal catalysts, in use, have a valence higher than zero, so that zero valent metals can be considered precatalysts. This has the consequence that zero-valent metal catalyst regeneration typically requires a reduction step to at least partially reduce the metal chloride to zero-valent metal. This is described in more detail later in this specification in connection with catalyst regeneration.

  A fourth class of catalysts that can be used in the process of the present invention are carbon-based catalysts. Activated carbon and graphite are examples of suitable carbon-based catalysts. In one embodiment, the carbon-based catalyst includes activated carbon.

Depending on the activated carbon, any carbon having a relatively high surface area, such as about 50 to about 3000 m ² or about 100 to about 2000 m ² (eg, about 200 to about 1500 m ² or about 300 to about 1000 m ² ) is included. Activated carbon can be derived from any carbonaceous material such as coal (eg, charcoal), nut shells (eg, coconut), and wood. Any form of activated carbon can be used, such as powdered, granulated, extruded, and pelleted activated carbon.

  In use, the carbon-based catalyst is typically at least partially chlorinated by a pre-chlorination step and / or a co-feed of HCl according to the method of the present invention. The carbon-based catalyst can also be at least partially fluorinated in use with any HF produced by dehydrofluorination of competing hydrochlorofluoroalkanes.

  The catalyst used in the present invention may be amorphous. This means that the catalyst does not exhibit substantial crystalline character when analyzed, for example, by X-ray diffraction. Alternatively, the catalyst may exhibit some crystalline characteristics in alumina (support) and / or metal oxide, or in carbon.

  For example, the metal oxide and / or metal halide catalyst can be partially crystalline. This means that 0.1-50% by weight of the catalyst is in the form of one or more crystalline compounds of the metal (s) in the catalyst. If a partially crystalline catalyst is used, it is preferably in the form of one or more crystalline compounds of the metal (s) in the catalyst, preferably 0.2-25% by weight of the catalyst, more preferably 0. 0.3 to 10% by weight, even more preferably 0.4 to 5% by weight.

Catalyst Pre-chlorination and / or HCl Cofeed An important feature of the process of the present invention is that (i) the metal-based catalyst is chlorinated prior to contacting the catalyst with the hydrochlorofluoroalkane to provide dehydrochlorination. Or (ii) contacting the catalyst with a hydrochlorofluoroalkane is performed in the presence of an HCl co-feed. Alternatively, both the catalyst prechlorination step (i) and the HCl cofeed (ii) can be used in the process of the present invention. Without being bound by theory, one or both of the catalyst prechlorination step (i) and the use of the HCl co-feed (ii) is surprising, depending on the combination such as hydrochlorofluoroalkane and reaction conditions. It is believed that over any undesired dehydrofluorination reaction will increase the selectivity of the desired dehydrochlorination and / or increase the stability of the catalyst in use.

The catalytic pre-chlorination step (i) includes, for example, diatomic chlorine (Cl ₂ ), ClF (eg, formed in situ as a mixture of Cl ₂ and hydrogen fluoride), and hydrogen chloride (HCl). Of any suitable chlorinating agent. In one embodiment, the catalyst is chlorinated with a chlorinating agent comprising HCl and /, or Cl _2. Preferably, the chlorinating agent comprises HCl.

  The catalysts described herein (especially metal oxide catalysts) are typically stabilized by heat treatment prior to use so that they are stable under the environmental conditions to which they are exposed in use. The catalyst is preferably stabilized by heat treatment in a nitrogen or nitrogen / air environment. In the art, this stage is often referred to as “calcination”. Many commercially available catalysts have already been calcined, and in one embodiment, the catalyst pre-chlorination step is performed on the pre-calcined catalyst.

Alternatively, it is relatively simple to incorporate a calcination step prior to catalyst prechlorination. For example, the catalyst (particularly the metal oxide catalyst) can be heat treated in a suitable atmosphere, including an atmosphere of nitrogen or an atmosphere having an oxygen level of about 0.1 to about 10% v / v in nitrogen. Alternatively, other oxidizing environments can be used. For example, suitable oxidant-containing environments include, but are not limited to, those containing a source of nitric acid, CrO ₃ , O ₂ , or Cl ₂ (eg, air). When used, the preliminary calcination step can be performed under the following conditions.

In one embodiment, the catalyst pre-chlorination step is performed on a pre-dried catalyst. Alternatively / additionally, it is relatively simple to incorporate a drying step at the beginning of the catalyst prechlorination. This can conveniently be carried out in a reactor in which a subsequent dehydrochlorination reaction is carried out. This can be accomplished by passing an inert gas (eg, nitrogen) over the catalyst at an elevated temperature. For example, the catalyst may be dried under inert gas with the following space velocity, drying time, and temperature.

In one embodiment, the catalyst pre-chlorination step is performed on the pre-fluorinated catalyst. Alternatively / additionally, if desired, it is relatively simple to incorporate a catalyst fluorination step at the beginning of the catalyst prechlorination. This can conveniently be carried out in a reactor in which a subsequent dehydrochlorination reaction is carried out. This can be accomplished by passing a fluorinating agent (eg, HF), optionally in combination with an inert gas (eg, nitrogen), over the catalyst at an elevated temperature. For example, a catalyst (especially a metal oxide catalyst) can be prefluorinated under the following conditions (especially with HF).

The pre-chlorination step is typically performed by passing a gas stream containing a chlorinating agent over the catalyst at an elevated temperature. This can conveniently be carried out in a reactor in which a subsequent dehydrochlorination reaction is carried out. The gas stream can be a substantially pure chlorinating agent (eg, HCl and / or Cl ₂ ). However, alternatively, the chlorinating agent can be passed over the catalyst in the presence of an inert gas (eg, nitrogen) to dilute the chlorinating agent at least initially. For example, a catalyst (especially a metal oxide catalyst) can be prechlorinated under the following conditions (especially with HCl).

Catalyst drying, fluorination (when used), and chlorination can be combined into a single procedure. This has the benefits of process economics and simplicity by optimizing catalyst activity, selectivity, and stability in a single step. In such a procedure, the catalyst is dried according to the conditions presented in Table 2. When the catalyst is fluorinated, the fluorinating agent (eg, HF) is often flowed over the catalyst at least initially, in addition to the inert gas stream (eg, N ₂ ), according to the conditions presented in Table 3. It is. The fluorinating agent flow is then stopped and then an inert gas flow will typically be used to purge any residual fluorinating agent catalyst. A chlorinating agent (eg, HCl) is then often flowed over the catalyst, at least initially, in addition to an inert gas stream (eg, N ₂ ) according to the conditions presented in Table 4.

  In the catalytic chlorination procedure described above, the inert gas stream is typically about 10 times after the chlorinating agent stream is activated, eg, after the chlorinating agent stream is activated, after the chlorinating agent stream is activated. Minutes to about 20 hours, preferably about 30 minutes to about 20 hours, for example about 1 hour to about 12 hours. Alternatively, if a chlorinating agent is detected in the chlorinated off-gas, the flow of inert gas can be cut off. The reactor temperature is then typically increased (see temperature range in Table 2 compared to Table 3) to promote catalytic chlorination. Optionally, when the catalyst prechlorination is complete, the chlorinating agent flow can be cut off and the inert gas flow can be resumed to purge any residual chlorinating agent catalyst.

  Of course, even when catalytic chlorination is not combined with catalyst drying (and optionally catalyst fluorination) in a single procedure, ie, pre-dried (and optionally pre-fluorinated) catalyst is When chlorinated, the chlorinating agent (eg, HCl) can be diluted with an inert gas (eg, nitrogen) during catalytic chlorination. The comparative amounts of chlorinating agent and inert gas diluent are typically in the ranges defined in Table 3 above.

  As an alternative to or in addition to catalytic prechlorination, the dehydrochlorination process of the present invention can be carried out in the presence of a co-feed of HCl. In other words, during the step of contacting a reagent stream comprising hydrochlorofluoroalkane with a catalyst to dehydrochlorinate at least a portion of the hydrochlorofluoroalkane, a feed of HCl can be fed to the reactor. HCl can be fed into the reactor separately and / or combined with hydrochlorofluoroalkane in the reagent stream.

  To avoid doubt, the HCl co-feed, when used, is present in the reactor from the dehydrochlorination of the hydrochlorofluoroalkane in excess of the amount of HCl present in the reactor in situ. Increase the amount of HCl. Indeed, in one embodiment, at least a portion of the HCl produced by dehydrochlorination of the hydrochlorofluoroalkane is recycled to the dehydrochlorination reactor to form at least a portion of the HCl co-feed. .

  In one aspect, at least a portion of the HCl co-feed comes from a previous method step that produces a hydrochlorofluoroalkane. Typically, the hydrochlorofluoroalkane that forms part of the reagent stream in the method of the invention is a (hydro) chloro (fluoro) alkane or (hydro) chloro (fluoro) alkene, preferably a hydrochloro (fluoro) alkane or hydrochloro ( Prepared by fluorination of fluoro) alkenes.

For example, HCFC-243fa and HCFC-244fa can be prepared by fluorination of 1,1,1,3,3-pentachloropropane (HCC-240fa) using HF according to the following equation:
CCl ₃ CH ₂ CCl ₂ H (HCC-240fa) + 4HF → CF ₃ CH ₂ CClFH (HCFC-244fa) + 4HCl
CCl ₃ CH ₂ CCl ₂ H (HCC-240fa) + 3HF → CF ₃ CH ₂ CCl ₂ H (HCFC-243fa) + 3HCl

  At least a portion of the HCl produced in the preparation of the hydrochlorofluoroalkane can be used in the HCl co-feed in the process of the present invention. Thus, in the above example, at least a portion of the HCl produced in the preparation of HCFC-244fa is used in the co-feed in the process of the invention for dehydrochlorinating HCFC-244fa to HFO-1234ze. obtain. Similarly, at least a portion of the HCl produced in the preparation of HCFC-243fa can be used in a co-feed in the process of the invention for dehydrochlorinating HCFC-243fa to HCFO-1233zd.

  When an HCl co-feed is used, the amount of HCl fed to the dehydrochlorination reactor is typically up to about 50 mol% based on the combined amount of hydrochlorofluoroalkane and HCl. In one embodiment, the amount of HCl fed to the dehydrochlorination reactor is up to about 40 mol%, preferably up to about 30 mol%, or about 20 mol%, based on the combined amount of hydrochlorofluoroalkane and HCl. For example, the maximum is about 10 mol%. Preferably, the amount of HCl fed to the dehydrochlorination reactor is at least about 1% or about 2%, such as at least about 5%, based on the combined amount of hydrochlorofluoroalkane and HCl.

  Without being bound by theory, the use of a co-feed of HCl that increases the concentration of HCl in the reactor is (i) the stability of the catalyst, ie the life of the catalyst, and / or (ii) the desired (hydro) It is believed to improve the selectivity of the (chloro) fluoroalkene to the dehydrochlorination product. The latter is particularly notable because the concentration of HCl that interferes with dehydrochlorination, and correspondingly increased selectivity for the dehydrochlorinated product compared to the dehydrofluorinated product may be expected. It's amazing.

  The exact preferred conditions of the process according to the invention depend, for example, on the nature of the reagents and products used and the catalyst. Some guidance regarding suitable and preferred reaction conditions is included herein below.

  The dehydrochlorination process of the present invention is typically performed at low to superatmospheric pressure, for example from about 0.1 to about 40 bara, such as from about 0.5 to about 20 bara, preferably from about 0.5 to about 10 bara. . Advantageously, the dehydrochlorination is carried out at about 1 to about 5 bara.

  Typically, the dehydrochlorination process of the present invention is carried out at a temperature of about 100 ° C to about 600 ° C, such as about 120 ° C to about 500 ° C, preferably about 150 ° C to about 450 ° C. Advantageously, the dehydrochlorination is carried out at a temperature of about 180 ° C to about 420 ° C.

  The method of the invention can be carried out in the gas phase or liquid phase. In general, the gas phase is preferred, especially when the catalyst comprises a metal oxide.

The contact time for a reagent stream containing hydrochlorofluoroalkane and the catalyst can be indicated by the space velocity (SV), which is the volumetric stream entering the reactor divided by the reactor volume. Based on a nominal 10 ml loading of the catalyst, a typical SV is about 0.1 min- ¹ to about 10 min- ¹ , preferably about 0.5 min- ¹ to about 7.5 min- ¹ . Preferably, it is about 1 minute- ¹ to about 5 minutes- ¹ .

  The process of the invention can be carried out in any suitable apparatus such as a static mixer, stirred tank reactor, or stirred gas-liquid separation vessel. The method can be performed batchwise or continuously. Either a batch process or a continuous process may be performed using a “one-pot” mode, or using two or more discrete reaction zones and / or reaction vessels. Preferably the reaction is carried out continuously. However, even in a “continuous” process, the process will need to be paused periodically, eg, for maintenance and / or catalyst regeneration.

  The catalyst regeneration can be performed by any suitable means. For example, a metal oxide catalyst (eg, a chromia-based catalyst) can be periodically regenerated by heating in air at a temperature of about 300 ° C. to about 500 ° C. Air can be used as a mixture with an inert gas such as nitrogen or a chlorinating agent. Alternatively, the catalyst (eg, metal oxide catalyst) can be continuously regenerated while being used by introducing an oxidizing gas, such as oxygen or chlorine, into the reactor. The above is later referred to herein as regenerative oxidation and is typically used to regenerate the coked catalyst and at least partially restore the activity of the catalyst.

  In one embodiment, regenerative oxidation is performed in the presence of a fluorinating agent (eg, HF) in addition to an oxidizing gas (eg, air). Typically this is done under the conditions previously defined herein in connection with catalytic prefluorination (see, eg, Table 3). This has the effect of partially fluorinating the catalyst (eg, metal oxide catalyst) in addition to reviving the activity of the catalyst by oxidation. This is later referred to herein as regenerated oxyfluorination.

  After regeneration with oxidant gas, it may be preferable to reduce the catalyst to remove any high oxidation state species remaining on or in the catalyst and reactor. This is later referred to herein as regenerative reduction. Such regenerative reduction step is preferred when the catalyst contains a zero valent metal. The regeneration reduction step may involve treatment with, for example, hydrogen under conditions sufficient to affect the necessary reduction. Alternatively, high oxidation state species can be converted to low oxidation state species by slow cooling, ie heating, the catalyst to a temperature at which the high oxidation state species decomposes. For example, chromium (VI) species can be converted to chromium (III) species in this manner.

  It may also be desirable to rechlorinate the catalyst (eg, metal oxide catalyst) after regenerative oxidation and / or regenerative reduction. The conditions previously described herein in connection with the prechlorination step (i) of the process of the present invention (see, eg, Table 4) are generally suitable for this regenerative chlorination. Regenerative chlorination is typically used to regenerate the catalyst (eg, in use and / or by regenerative oxyfluorination) to regenerate any undesired dehydrofluorination reaction. This restores the desired selectivity to dehydrochlorination and / or increases the stability of the catalyst in use.

  In one embodiment, for example, the catalyst for the process of the present invention includes a metal oxide, and catalyst regeneration includes both regenerative oxidation and regenerative chlorination. In one aspect, such catalyst regeneration is performed using regenerative oxidation and regenerative chlorination combined with one regenerative oxychlorination procedure. This has the benefit of economics and simplicity of the process by restoring catalyst activity, selectivity, and stability in a single step.

  Regenerative oxychlorination can be performed by heating the catalyst in the presence of a gas containing an oxidant and a chlorinating agent. Typically this is carried out at a temperature of about 250 ° C to about 550 ° C, preferably about 300 ° C to about 500 ° C. The oxidizing gas can be oxygen or chlorine, preferably oxygen. The chlorinating agent can be chlorine or HCl, preferably HCl. When subjected to the temperature ranges described above, the conditions previously described herein in connection with the pre-chlorination step (i) of the process of the present invention (see, eg, Table 4) are generally: Suitable for this regenerative oxychlorination, the space velocity for the oxidizing gas is in the range of the space velocity described for the chlorinating agent.

  In another embodiment, for example, where the catalyst for the process of the present invention comprises a metal oxide, catalyst regeneration includes both regenerated oxyfluorination and regenerated chlorination.

  The invention is illustrated by the following non-limiting examples.

Sintered Ni small circles were generated by reducing NiF ₂ with H ₂ . The catalyst was then charged into the reactor and re-reduced in the reactor with H ₂ before starting the flow of 244bb over Komaru, conditions:
・ Temperature = 400 ℃
-Flow rate of 244bb = 5ml / min-Reactor = Glass-lined stainless steel with glass wool and rod support-1.2g sintered Ni Komaru

Initially, the conversion of 244bb was inadequate. The supply of 244bb was cut off, and then small circles were reduced with H ₂ for the second time. Although the conversion increased temporarily to about 14%, the reaction was less selective for the conversion of 1234yf and 244bb, which was substantially reduced in less than 3 hours. The supply of 244bb was cut off and the small circle was treated with HCl (2.5 hours at 400 ° C., 50% in N ₂ ), which increased the conversion of 244bb to 17% and the reaction was high relative to 1234yf. It was selectivity. In addition, the relatively high 244bb conversion and 1234yf selectivity were maintained for about 4 hours. The results are summarized below.

  The results show a surprising beneficial effect in conversion, especially selectivity, for the 244bb dehydrochlorination to 1234yf by chlorinating the catalyst prior to contacting it with the 244bb reagent stream.

The invention is defined by the following claims.

Claims (27)

A method for the preparation of a (hydro) (chloro) fluoroalkene, wherein a reagent stream comprising hydrochlorofluoroalkane is contacted with a catalyst in a reactor to dechlorinate at least a portion of said hydrochlorofluoroalkane. Hydrogenating to produce a product stream comprising the (hydro) (chloro) fluoroalkene and hydrogen chloride (HCl), wherein the catalyst is selected from a zerovalent metal catalyst and the contacting step is in the gas phase Carried out in the presence of HCl co-feed ,
The catalyst is chlorinated prior to contacting it with the reagent stream comprising the hydrochlorofluoroalkane, and
The method wherein the zerovalent metal catalyst comprises nickel . The method of claim 1 , wherein the catalyst is chlorinated with a chlorinating agent comprising hydrogen chloride (HCl), chlorine (Cl ₂ ), or mixtures thereof. The process according to claim 1 or 2 , wherein the chlorination comprises contacting the catalyst with a chlorinating agent at a temperature of 200C to 600C. 4. The process of claim 3 , wherein the catalyst is contacted by a fluid stream of the chlorinating agent having a space velocity of 0.1 min- ^{1 to} 3 min- ¹ for 1 hour to 48 hours. Chlorinating agent is diluted by the presence of an inert gas, the method according to any one of claims 2-4. The method of claim 5 , wherein the inert gas is nitrogen. The method according to any of claims 1 to 6 , wherein the chlorination step is combined in a single procedure with a catalyst drying step. The amount of HCl fed to the reactor, based on the amount of a combination of a HCl fed to the hydro chlorofluoroalkanes the reactor, the maximum 50 mol%, according to any one of claims 1-7 the method of. Wherein the amount of HCl fed to the reactor, based on the amount of a combination of a HCl fed to the reactor with hydrochlorothiazide fluoroalkane is at least 1 mol%, according to any one of claims 1-8 the method of. At least a portion of the HCl in said product stream, is recycled to the reactor, which constitutes at least a part of the HCl co-feed process according to any one of claims 1-9. 11. A method according to any of claims 1 to 10 , wherein at least a portion of the HCl co-feed comes from a previous method step that produces the hydrochlorofluoroalkane. The (hydro) (chloro) fluoro alkene _is a _{C 3 to 7} (hydro) (chloro) fluoro alkene, the hydro chlorofluoroalkanes _is a _{C 3 to 7} hydro chlorofluoroalkanes of claim 1-11 The method according to any one. The _{C 3 to 7} (hydro) (chloro) fluoro alkene, (hydro) (chloro) fluoro propene, the _{C 3 to 7} hydro chlorofluoroalkanes is a hydrochlorothiazide fluoro propane, according to claim 12 Method. The (hydro) (chloro) fluoropropene is selected from 1-chloro-3,3,3-trifluoropropene (CF ₃ CH═CHCl, HCFO-1233zd) and 2-chloro-3,3,3-trifluoropropene ( CF ₃ is _{CHCl = CH 2, HCFO-1233xf} ) hydro chlorofluorohydrocarbons propene selected from the method of claim 13. The hydrochlorofluorocarbon fluoro propane, 1,1-dichloro-3,3,3-trifluoro-propane _{(CF 3 CH 2 CHCl 2,} HCFC-243fa), for preparing a HCFO-1233zd, in claim 13 The method described. The hydrochlorofluorocarbon fluoro propane, 1,2-dichloro-3,3,3-trifluoro-propane _{(CF 3 CHClCH 2 Cl, HCFC} -243db), for preparing a HCFO-1233xf, claim 13 the method of. The (hydro) (chloro) fluoropropene is a 1,3,3,3-tetrafluoropropene (CF ₃ CH═CHF, HFO-1234ze) and 2,3,3,3-tetrafluoropropene (CF ₃ CF═ a hydrofluoropropenes selected from CH _2, HFO-1234yf), the method of claim 13. 18. The process of claim 17 , for preparing HFO-1234yf, wherein the hydrochlorofluoropropane is 2-chloro-1,1,1,2-tetrafluoropropane (HCFC-244bb). The process of claim 17 for preparing HFO-1234ze, wherein the hydrochlorofluoropropane is 3-chloro-1,1,1,3-tetrafluoropropane (HCFC-244fa). The dehydrochlorination is carried out at a pressure of 10~4000kPa (0.1~40bara), The method of any of claims 1-19. 21. The method of claim 20 , wherein the dehydrochlorination is performed at a pressure of 100 to 500 kPa (1 to 5 bara). The method according to any one of claims 1 to 21 , wherein the dehydrochlorination is performed at a temperature of 100C to 600C. The process according to claim 22 , wherein the dehydrochlorination is carried out at a temperature between 180C and 420C. 24. A method according to any of claims 1 to 23 , wherein the reagent stream comprising hydrochlorofluoroalkane in contact with the catalyst has a space velocity of 0.1 min- ¹ to 10 min- ¹ . 25. The method of any of claims 1 to 24 , wherein the process is continuous and the catalyst is periodically regenerated by one or more of regenerative oxidation, regenerated oxyfluorination, regenerative reduction, or regenerative chlorination. The method described in 1. 26. The method of claim 25 , wherein the catalyst is regenerated by (i) regenerative oxidation or (ii) regenerated oxyfluorination, followed by (iii) regenerative chlorination. 26. The method of claim 25 , wherein the catalyst is regenerated by regenerative oxychlorination.